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2001 STANDARD for SOUND RATING OF DUCTED AIR MOVING AND CONDITIONING EQUIPMENT

Standard 260 4301 NORTH FAIRFAX DRIVE

l

ARLINGTON, VIRGINIA 22203


IMPORTANT

SAFETY RECOMMENDATIONS It is strongly recommended that the product be designed, constructed, assembled and installed in accordance with nationally recognized safety requirements appropriate for products covered by this standard. ARI, as a manufacturers' trade association, uses its best efforts to develop standards employing state-of-the-art and accepted industry practices. However, ARI does not certify or guarantee safety of any products or systems designed, tested, rated, installed or operated in accordance with these standards or that any tests conducted under its standards will be non-hazardous or free from risk.

Note: This is a new standard. Foreword: Ducted Equipment must be sound rated in relation to its various individual Sound Components to describe it acoustically and to provide the necessary information for predicting application sound levels. This standard addresses the sound rating of these various Sound Components. Ducted airconditioning equipment can have ducted discharge, ducted inlet, free inlet (or free discharge) combined with casing radiated, or casing radiated Sound Components depending on its specific manufactured configuration. All Sound Components are acoustically described/rated by utilizing a "Mapped" Sound Rating approach that is typically referenced to the product's supply fan operating map. The supply fan is contained in the Base Unit of the product. In addition, this standard defines an approach to account for and add the acoustical effects of product Appurtenances (such as modulation devices or inlet/discharge plenums) and Other Sound Sources (such as the refrigeration circuit, exhaust fans, etc.) to the Base Unit Mapped Sound Rating. Thus, Mapped Sound Ratings can be developed for a given product configuration and each of its various Sound Components. All ducted product Sound Components are rated utilizing a Reverberation Room Technique, modeled after AMCA Standard 300. Reverberation room tests are conducted using a Comparison Method and a Reference Sound Source calibrated in accordance with ARI Standard 250. Sound ratings are in the form of Octave Band Sound Power Levels (dB) from 125 to 8,000 Hz derived from One-Third Octave Band (dB) measurements for the various product Sound Components. Sound ratings may be provided for the 63 Hz Octave Band if the reverberation room has been qualified in accordance with ARI Standard 280. A listing of current ARI Sound Standards is located in Appendix C.

Price $10.00 (M) $20.00 (NM) Printed in U.S.A.

8Copyright 2001, by Air-Conditioning and Refrigeration Institute Registered United States Patent and Trademark Office


TABLE OF CONTENTS SECTION

PAGE

Section 1.

Purpose............................................................................................................... 1

Section 2.

Scope.................................................................................................................. 1

Section 3.

Definitions ......................................................................................................... 1

Section 4.

Requirements for Acquiring Mapped Sound Data............................................. 3

Section 5.

Sound Power Level Calculations and Ratings ................................................... 7

Section 6.

Minimum Data Requirements for Published Sound Ratings............................. 9

Section 7.

Conformance Conditions ................................................................................. 10 FIGURES

Figure 1.

Typical Ducted Discharge Test Setup ............................................................... 5

Figure 2.

Typical Ducted Inlet Test Setup ........................................................................ 5

Figure 3.

Typical Free Inlet Combined with Casing Radiated Test Setup ........................ 5

Figure 4.

Typical Casing Radiated Test Setup .................................................................. 6

Figure 5.

Typical Free Inlet Test Setup ............................................................................. 6 APPENDICES

Appendix A.

References - Normative ................................................................................... 11

Appendix B.

References - Informative.................................................................................. 12

Appendix C.

ARI Standards on Sound - Informative............................................................ 13

Appendix D.

Atkins Sound Attenuation Adjustments for Acoustic Test Duct Elbows - Normative ......................................................................................... 14

Appendix E.

Effects of Other Sources - Normative.............................................................. 15

Appendix F.

Supply Fan Modulation Device Effects - Normative....................................... 16

Appendix G.

Method of Processing Acquired Data - Normative.......................................... 17


TABLES FOR APPENDICES Table C1.

ARI Standards on Sound - Informative............................................................ 13


ARI STANDARD 260-2001

SOUND RATING OF DUCTED AIR MOVING AND CONDITIONING EQUIPMENT Section 1. Purpose 1.1 Purpose. The purpose of this standard is to establish a method of sound rating the indoor portions of ducted air moving and conditioning equipment and to provide definitions; requirements for acquiring mapped sound data; Sound Power Level calculations and ratings; minimum data requirements for published sound ratings; and conformance conditions. 1.1.1 Intent. This standard is intended for the guidance of the industry, including manufacturers, engineers, installers, contractors and users. 1.1.2 Review and Amendment. This standard is subject to review and amendment as technology advances. Section 2. Scope 2.1 Scope. This standard applies to all ducted air moving and conditioning equipment containing fans as defined in Section 3 of this standard. Examples of such equipment when ducted are: a. b. c. d. e. 2.2

Unitary Air-Conditioners, as defined in ARI Standard 210/240 and ARI Standard 340/360 ARI-Source Unitary Heat Pumps, as defined in ARI Standard 340/360 Water-Source Heat Pumps, as defined in ISO 13256-1 Fan-Coil Air-Conditioners, as defined in ARI Standard 440 Central-Station Air-Handling Units, as defined in ARI Standard 430

Exclusions. This standard does not apply to: a. b. c. d.

e.

Air Control and Distribution Devices, which are covered by ARI Standard 880 Packaged Terminal Air-Conditioners, which are covered by ANSI/ARI Standard 300 Outdoor sound from outdoor portions of Ducted Equipment that would be covered under ARI Standards 270 and 370 The sound radiated from ductwork attached to the fan and/or equipment when such ductwork is not offered by the manufacturer as a standard part of the equipment The casing (base pan) radiated sound

component for rooftop or down draft products Section 3. Definitions All terms in this document shall follow the standard industry definitions established in the current edition of ASHRAE Terminology of Heating, Ventilation, Air-Conditioning and Refrigeration, unless otherwise defined in this section. 3.1 Acoustic Test Duct. The duct used to convey the sound of the unit configuration under test to the reverberation room during a ducted discharge or the ducted inlet sound component test. A Duct End Correction (E) must be added to the sound data measured in the reverberation room to account for the presence of an open-ended duct terminating in the reverberation room. 3.2 Acoustic Test Duct Elbow. An elbow added to the Acoustic Test Duct during a reverberation room test to facilitate testing. An adjustment must be made (in addition to the Duct End Correction) to the sound data to account for the presence of the Acoustic Test Duct Elbow. Appendix D of this standard defines the Atkins sound attenuation adjustments. 3.3 Base Unit. A factory-made encased assembly consisting of one or more fans meant to be connected to a duct and other necessary equipment to perform one or more of the functions of circulating, cleaning, heating, cooling, humidifying, and mixing of air, but which does not always include a source of heating or cooling. 3.3.1 Appurtenance. An addition to a Base Unit for purposes of control, isolation, safety, static pressure regain, wear etc. Examples of Appurtenances include: a.

b. c. d. e. f. g. h. i.

Coil(s) 1. Cooling coil 2. Cooling and dehumidifying coil 3. Water spray (wetted coil) 4. Heating coil Electric heater(s) Air filter Dampers Moisture eliminator Fan-motor drive Gas heat exchangers Inlet or discharge plenums Modulating devices in the fan inlet/discharge

1


ARI STANDARD 260-2001

j.

b.

Application duct geometries (such as duct elbow configurations)

c. 3.4 Comparison Method. A method of determining Sound Power Level of a source under test in a reverberation room by comparing the average Sound Pressure Level of that source to the average Sound Pressure Level of a Reference Sound Source of known Sound Power Level output. The difference in Sound Power Level is equal to the difference in Sound Pressure Level when conditions in the room are the same for both sets of measurements. 3.5 Duct End Correction, E. Accounts for the acoustic energy in an Acoustic Test Duct that is reflected back towards the source. A method for computing E is defined in 5.2.1 of this standard. 3.6 Ducted Equipment. Heating, ventilating and airconditioning equipment having one or more supply fans. The equipment may be configured with either: a. b. c.

Free inlet(s) with ducted discharge(s) Ducted inlet(s) with free discharge(s) Ducted inlet(s) and ducted discharge(s)

This equipment may be ducted in various configurations horizontally and vertically, and may incorporate multiple inlets and outlets. 3.7 Effective Diameter, D. Diameter of an Acoustic Test Duct and is equal to either the diameter, ft [m], of a circular duct or the Effective Diameter, ft [m], of a rectangular duct.

Direct-drive products with variable frequency drives Direct-drive products with discrete speed taps

Note: Special case –when a supply fan is used in conjunction with a return fan in the Base Unit (See Appendix E of this standard). 3.11 Octave Band. A band of sound covering a range of frequencies such that the highest is twice the lowest. The Octave Bands used in this standard are those defined in ANSI Standard S1.11. 3.12 One-Third Octave Band. A band of sound covering a range of frequencies such that the highest frequency is the cube root of two times the lowest. The One-Third Octave Bands used in this standard are those defined in ANSI Standard S1.11. 3.13 Reference Sound Source (RSS). A portable, aerodynamic sound source that produces a known stable broad band sound power output. 3.14 Reverberation Room Technique. A technique used to derive the Sound Power Level of Ducted Equipment Sound Components. The technique utilizes an Acoustic Test Duct coupled to a reverberation room to measure the ducted inlet or ducted discharge sound. Other setup configurations allow the testing of the casing radiated or free inlet (or free discharge) combined with the casing radiated Sound Components. This technique is incorporated in AMCA Standard 300. 3.15 "Shall" or "Should". "Shall" or "should" shall be interpreted as follows:

D is given by the following expression: 1/ 2

æ 4 x AREA ö D=ç ÷ π ø è

where:

(1)

AREA = Cross-sectional area of the duct, ft2 [m2] 3.8 Hertz (Hz). A unit of frequency equal to one cycle per second. 3.9 Low Frequency Data. Data in the 63 Hz Octave Band (50, 63 and 80 Hz One-Third Octave Bands). 3.10 Mapped Sound Rating. A rating based upon tests performed across the range of operating conditions typically defined for the product supply fan map, in the Base Unit, and as defined by the product manufacturer. These products include: a.

Belt-driven products with or without variable frequency drives

3.15.1 Shall. Where "shall" or "shall not" is used for a provision specified, that provision is mandatory if compliance with the standard is claimed. 3.15.2 Should. "Should" is used to indicate provisions which are not mandatory but which are desirable as good practice. 3.16 Sound Components. The various Sound Sources emanating from the product that need to be independently defined to adequately describe a product’s acoustic effect on a typical application. Depending on the configuration of the equipment the Sound Components that need to be defined consist of several or all the following: a. b. c.

2

Ducted discharge Free inlet (or free discharge) combined with casing radiated Casing radiated


ARI STANDARD 260-2001

d. e.

Ducted inlet Free inlet (and/or free discharge)

3.17 Sound Power Level, Lw. This is ten times the logarithm to the base ten of the ratio of the sound power radiated by the source to a reference sound power, expressed in decibels (dB). The reference sound power used in this standard is 1 picowatt (pW). 3.18 Sound Pressure Level, Lp. This is twenty times the logarithm to the base ten of the ratio of a given sound pressure to a reference sound pressure of 20 :Pa, expressed in decibels (dB). 3.19 Sound Sources. a. b. c.

Base Unit. Sound generated by the supply fan(s) in the Base Unit. Appurtenance. Sound generated or attenuated due to the Appurtenance having supply fan airflow through it. Other. Sound generated by an element that is not dependent on the supply fan airflow of the product. The refrigerant circuit, airborne noise from a variable frequency drive (VFD) ventilation fan, motor noise due to a VFD, gas burner combustion noise, and exhaust fans are examples of Other Sound Sources.

The three Ducted Equipment configurations addressed by this standard are equipment with: a. b. c.

Free inlet(s) with ducted discharge(s) Ducted inlet(s) with free discharge(s) Ducted inlet(s) and ducted discharge(s)

The three equipment configurations have the following Sound Components: 4.1.1 Equipment with Free Inlet(s) and Ducted Discharge(s). The following Sound Power Levels shall be determined for this configuration: a. b. c.

Note: The free inlet combined with casing radiated sound power component shall not be derived from separate free inlet and casing radiated sound tests. 4.1.2 Equipment with Ducted Inlet(s) and Free Discharge(s). The following Sound Power Levels can be determined for this configuration: a. b. c.

Section 4. Requirements for Acquiring Mapped Sound Data 4.1 General Overview. This standard incorporates a Reverberation Room Technique utilizing AMCA Standard 300 to obtain the Sound Power Levels of the various Sound Components for ducted air-moving and air-conditioning equipment. It goes beyond AMCA Standard 300 which is for rating fans, by adding the effects of Appurtenances and Other Sound Sources to the Base Unit to obtain the Mapped Sound Rating of a given product configuration. Sound Power Levels shall be obtained utilizing the Comparison Method and a Reference Sound Source calibrated per ARI Standard 250. The One-Third Octave Band Sound Pressure Levels of Sound Components can be measured to obtain the Sound Power Levels required to rate each sound component of the equipment. Products having multiple ducted inlets or multiple ducted discharges on a common face that are meant by the manufacturer to join into a common duct shall be ducted into the reverberation room and tested at the same time. A Duct End Correction of only one of the ducts shall be made. However, if products have multiple ducted inlets or discharges on a common face or different faces, and are not joined into a common duct, each shall be ducted into the reverberation room and tested separately. Duct End Corrections shall be made for each of the ducts.

Free inlet combined with casing radiated Ducted discharge Free inlet

Ducted inlet Casing radiated combined with free discharge Free discharge

Note: The free discharge combined with casing radiated sound power component shall not be derived from separate free discharge and casing radiated sound tests. 4.1.3 Equipment with Ducted Inlet(s) and Ducted Discharge(s). The following Sound Power Levels can be determined for this configuration: a. b. c.

Ducted inlet Casing radiated Ducted discharge

4.2 Testing Considerations. All Ducted Equipment is acoustically described by conducting Mapped Sound Rating tests. Mapped Sound Ratings for each Sound Component of a product are obtained by first mapping the supply fan in the Base Unit. The Appurtenance and Other Sound Sources are added as necessary to a supply fan sound map of the Base Unit. 4.2.1 Base Unit. A sufficient number of speed curves and test points along each speed curve shall be evaluated to ensure that the difference between adjacent test points does not exceed 5 dB for any given One-Third Octave Band. At a minimum, Base

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ARI STANDARD 260-2001

Acoustic Test Duct Elbow is employed, adjustments shall be added to the sound data to account for attenuation of the Acoustic Test Duct Elbow using the Atkins adjustments as given in Appendix D.

Units shall be tested along the highest and lowest speed curves across the full operational map as specified by the manufacturer. 4.2.2 Appurtenances. A sufficient number of test data points shall be evaluated to ensure that the acoustical effect of the Appurtenance on the Base Unit is understood. The objective of the test is to determine if the Appurtenance can be represented by an averaged acoustical effect or if it must be described as a function of airflow velocity.

4.3.1.1 Orifice End Plate. The orifice end plate, as described in AMCA Standard 300 (Appendix C, Section C2), shall not be used to control the Acoustic Test Duct airflow in this standard. 4.3.2 Casing Radiated Combined with a Free Inlet or Free Discharge. All casing radiated with free inlet or free discharge Sound Components shall be tested per AMCA Standard 300 (Section 5).

4.2.2.1 Mechanical Airflow Control Device. The effects of a mechanical airflow control device (excluding variable frequency drives) shall be defined as outlined in AMCA Standard 300 (Appendix G). 4.2.3 Other Sources. A sufficient number of operating conditions shall be evaluated to ensure that the acoustical effects of the Other Sound Sources on the Base Units are understood. 4.2.3.1 Refrigerant Circuit Sources. Refrigerant circuit related sources are identified and defined only in reference to the ARI thermal rating standard operation point for a given product (see Appendix E). 4.2.3.2 Exhaust and Return Fans. The effects of the exhaust and return fan Sound Source shall be evaluated at a nominal static pressure and airflow specified by the manufacturer (see Appendix E). 4.2.3.3 Burners. The effects of the burner Sound Source shall be evaluated at the input rate and gas type specified on the nameplate. 4.3 Method of Test. All sound tests shall be conducted utilizing a Reverberation Room Technique modeled after AMCA Standard 300. However, the specific test setup will depend on the product Sound Components being tested. 4.3.1 Ducted Sound Components. For ducted inlet and ducted discharge components tested in accordance with AMCA Standard 300 (Section 5), the Duct End Correction (E) must be added to each One-Third Octave Band for all products. The addition of the Duct End Correction (E) provides the user with the sound power that would be transmitted into a nonreflecting duct system. Although a straight Acoustic Test Duct is preferred for ducted component tests, an Acoustic Test Duct Elbow may be used to accommodate test facility issues. If an

4

4.3.3 Casing Radiated Sound. For the casing radiated Sound Component, AMCA Standard 300 (Appendix G) shall be used to determine the Sound Power Level. 4.4

Test Equipment and Facilities. 4.4.1 Reverberation Room Instrumentation. The reverberation room instrumentation shall meet or exceed ANSI Standard S12.31, Section 4. 4.4.2 Reverberation Room Qualification. The reverberation room used in testing shall be qualified in accordance with ANSI Standards S12.31 and S12.32 using frequency rather than noise source position as the independent variable (and ARI Standard 280 if low frequency Sound Power Levels are to be determined). 4.4.3 Reference Sound Source (RSS). The Reference Sound Source shall be calibrated in accordance with ARI Standard 250. 4.4.4 Equipment Size. For reverberation room testing, the total equipment volume, including ductwork, shall not exceed 5 % of the volume of the reverberation room. 4.4.5 Use of Windscreen. During testing, a foam ball windscreen may be used on the microphone. The effect of the windscreen on the microphone response shall not be more than + 1 dB for frequencies of 100 to 4,000 Hz or + 1.5 dB for frequencies from 4,000 to 10,000 Hz. Sound measurements shall not be made with air velocities over the microphone exceeding 1,056 ft/min [5.4 m/s]. 4.4.6 Airflow Limitation. For sound test measurements made within a test room in accordance with AMCA Standard 300, it is recommended that the airflow of the test unit, in cfm [m3/min], shall not exceed, numerically, the room volume in ft3 [m3].


ARI STANDARD 260-2001

4.4.7 Test Unit Airflow Measurements. All test airflow measurements shall be made in accordance with ANSI/AMCA Standard 210. 4.5

General Test Setup 4.5.1 Ducted Discharge Tests. For this test the unit discharge is ducted into the reverberation room using an Acoustic Test Duct. The sound power of the ducted discharge shall be determined using AMCA Standard 300 (Section 5, Figure 3). The test configuration will typically be as shown in Figure 1. For ducted discharge tests, it is recommended that the Acoustic Test Duct be three effective duct diameters in length, but not less than 3.0 ft [0.91 m]. However, duct lengths up to five effective duct diameters are permissible if needed for setup or airflow performance measurements.

Figure 2. Typical Ducted Inlet Test Setup 4.5.3 Free Inlet (or Free Discharge) Combined with Casing Radiated Test. For this test, the unit discharge (the inlet) is ducted outside of the reverberation room. The discharge is ducted through a hole in the reverberation room wall, with the duct effectively lagged to prevent sound breakout into the reverberation room. The sound power of the free inlet (or discharge) combined with casing radiated sound shall be determined using AMCA Standard 300 (Section 5, Figure 2 for inlet and Figure 3 for discharge). The test configuration will typically be as shown in Figure 3.

Figure 1. Typical Ducted Discharge Test Setup 4.5.2 Ducted Inlet Tests. For this test the unit inlet is ducted into the reverberation room using an Acoustic Test Duct. The sound power of the ducted inlet shall be determined using AMCA Standard 300 (Section 5, Figure 2). The test configuration will typically be as shown in Figure 2. For ducted inlet tests, it is recommended that the Acoustic Test Duct be one effective duct diameter in length, but not less than 3.0 ft [0.91 m]. However, duct lengths up to five effective duct diameters are permissible if needed for setup or airflow performance measurements.

Figure 3. Typical Free Inlet Combined with Casing Radiated Test Setup 4.5.4 Casing Radiated Test. The casing of the unit must be in the reverberation room with both the inlet and the discharge ducted out of the test space. The attached ductwork must be effectively lagged to prevent significant duct sound radiation. The sound power shall be determined using AMCA Standard 300 (Appendix G). The test configuration will typically be as shown in Figure 4.

5


ARI STANDARD 260-2001

If the manufacturer does not define the supply or return opening, it is recommended that the Acoustic Test Duct be sized for a maximum of 2000 ft/min [10.2 m/s]. The ratio of the longer to the shorter sides of the rectangular duct cross section shall not exceed four unless this is not possible due to the manufacturer’s specifications. 4.5.6.2 Ductwork Connection. Ductwork shall be connected to the unit under test using a flexible connector. All flexible duct connectors shall be appropriately treated to retain flexibility and to contain the sound within the duct. Figure 4. Typical Casing Radiated Test Setup 4.5.5 Free Inlet or Free Discharge. For this test, the free inlet or free discharge of the unit must be connected through a hole in the reverberation room wall with the minimum amount of duct required to provide a proper seal. The Sound Power Level shall then be determined using AMCA Standard 300 (Section 5). The test configuration for free inlet will typically be as shown in Figure 5.

4.5.6.3 Construction of Test Ductwork. Ductwork used in the determination of ducted inlet and ducted discharge sound power shall be of a high transmission loss construction. The ductwork shall be constructed, at a minimum, of either: a. 18-gauge sheet metal stiffened by a ¾ in thickness gypsum board attached by sheet metal screws (on 6 in centers) and adhesive to the exterior of the duct, or b. Round sheet metal or PVC duct with a 1 lb/ft2 limp exterior acoustical barrier, or

c. ¾ in plywood. For high aspect ratio ducts it may also be necessary to stiffen the ¾ in plywood. 4.5.7 Duct Static Pressure Taps. Shall be per ASHRAE Standard 37 (Section 6). Figure 5. Typical Free Inlet Test Setup 4.5.6 Ductwork Required for Testing. Ductwork attached to the unit under test may influence the sound measured. Thus, care should be taken in the attachment and treatment of all ductwork. 4.5.6.1 Ductwork Size. Ductwork shall be sized to match the manufacturer's recommended supply or return opening and shall maintain a constant cross section.

6

4.5.8 Acoustic Test Ducts and Acoustic Test Duct Elbow. For testing of ducted inlet or discharge, straight Acoustic Test Ducts are recommended. However, the standard allows for the use of an Acoustic Test Duct Elbow due to facility issues. The use of an Acoustic Test Duct Elbow, its description, and the adjustments applied must be stated. If elbows are needed, the adjustments given by Atkins must be used (see Appendix D). 4.5.9 Acoustic Duct Flow Considerations. It is recommended that the Acoustic Test Duct be sized for a maximum of 2000 ft/min [10.2 m/s], unless this is not possible due to the manufacturer’s specifications.


ARI STANDARD 260-2001

c. d.

4.6 Data Acquisition. For each of the mapped operating points defined by measurements made in accordance with ANSI/AMCA Standard 210, measure the corresponding OneThird Octave Band Sound Pressure Levels. These Sound Pressure Levels shall be measured for the desired Sound Components for the Base Unit, Appurtenances, and Other Sound Sources over the mapped operating range in accordance with the appropriate sections of AMCA Standard 300 and this standard.

e. f. g. 4.6.2

4.6.1 Information to be Recorded. The following shall be compiled and recorded for measurements that are made according to the requirements of this Standard. The following is a list of data required to document the noise ratings supplied per this standard:

c.

d. e. f. g. h.

i. j. k.

Description of unit under test One-Third Octave Band Sound Power Levels with Duct End Corrections (if applicable) included, dB One-Third Octave Band Duct End Corrections, dB, and description of how duct was terminated in the reverberation room Duct internal height, width, and length dimensions, ft [m] Acoustic Test Duct Elbow Octave Band correction (if used) Acoustic Test Duct Elbow internal height, width and length dimensions (if used), ft [m] Description of thermal conditions during test Airflow, cfm [m3/s], duct static pressure, in H2O [kPa], fan speed, rpm [rev/s], fan motor BHP for each test point Sound component measured Test date Facility used

4.6.1.1

Unit Under Test. a.

b.

Description of Base Unit shall include information to clearly identify the unit under test such as fan type and size, cabinet wall construction and size, motor manufacturer and size Operating conditions (fan speed, rpm [rev/s], airflow cfm [m3/s], fan static pressure, in H2O [kPa], and air density, lb/ft3 [kg/m3])

Thermal Conditions During Test. a. b. c.

4.6.3 a. b.

Installation/mounting details Description of Appurtenances Description of Other Sources Acoustic Test Duct dimensions, ft [m] Acoustic Test Duct Elbow dimensions, ft [m]

Air temperature, oF [oC] Relative humidity, % Barometric pressure, in Hg [kPa]

Instrumentation. a. b.

The equipment used for the measurements, including name, type, serial number and manufacturer Description of Reference Sound Source used

Section 5. Sound Power Level Calculations and Ratings 5.1 General. This standard utilizes an Octave Band Sound Power Level rating system based on One-Third Octave Band Sound Pressure Level test data. The procedure for obtaining the Octave Band power level rating depends on the Sound Component being considered. Non-ducted Sound Components (casing radiated, free inlet combined with casing radiated, and free components) are obtained directly from the Sound Pressure Level data by utilizing Equation 2 in 5.2. Ducted Sound Components (ducted discharge or ducted inlet) must include Duct End Corrections and effects of the Acoustic Test Duct Elbow, if used during the sound test. A flow chart of how the data is processed for these two categories of Sound Components is presented in Appendix G. 5.2 Method of Processing Acquired Data. All of the measured One-Third Octave Band Sound Pressure Level data acquired in Section 4 shall be converted to One-Third Octave Band Sound Power Levels using Equation 2. Adjustments for Duct End Correction (E), as outlined in 5.2.1 and 5.2.2, shall be added to the calculated One-Third Octave Band Sound Power Levels when required for ducted Sound Components. Lw(n) = Lp(n) + [Lwr(n) – Lpr(n)] + E(n)

(2)

where: Lw(n) = Lp(n) =

Test unit Sound Power Level, dB, in the nth One-Third Octave Band Test unit measured Sound Pressure Level, dB, in the nth One-Third Octave Band

7


ARI STANDARD 260-2001

Lwr(n) = RSS Sound Power Level, dB, in the nth OneThird Octave Band Lpr(n) = RSS measured Sound Pressure Level, dB, in the nth One-Third Octave Band E(n) = Duct End Correction, dB, in the nth One-Third Octave Band when required Note: the Sound Pressure Levels of Lp(n) and Lpr(n) shall be corrected for ambient intrusion per AMCA Standard 300 (Section 6.2.1). 5.2.1 Calculation of the Duct End Correction (E). For ducted inlet or discharge elements that are tested in accordance with this standard, the Duct End Correction (E) must be added to each One-Third Octave Band Sound Power Level. The addition of the Duct End Correction (E) to the tested Sound Power Levels will provide the user with the sound power that would be transmitted into a non-reflecting duct system. Additionally, Duct End Correction values in Octave Bands shall be calculated as shown in 5.5 for inclusion as part of a unit’s ducted ratings. For a ducted inlet or discharge, the value for the Duct End Correction (E) can be expressed by the following two equations (from ASHRAE Algorithms for HVAC Acoustics), one for an Acoustic Test Duct penetrating into the free space of the reverberant room and the other for an Acoustic Test Duct terminating flush with the reverberant room wall (Equations (3) and (4) respectively). These expressions shall be used to calculate the correction (E) at the center frequencies of each One-Third Octave or Octave Band. For a duct terminating at a distance greater than or equal to D from the reverberation room wall, use the following equation:

Co D

)

= One-Third Octave Band center frequency, (Hz) = Speed of sound in air, ft/s [m/s] = Diameter, ft [m] of a circular duct or the Effective Diameter of a rectangular duct (as shown in Equation 1)

For a duct terminating flush or at a distance less than D from the reverberation room wall, use the following equation: 1.88

æ 0.8 C o ö E = 10 log10 (1 + çç ÷÷ èπ f D ø

8

5.3 Determination of Equipment Octave Band Sound Power Levels. One-Third Octave Band Sound Power Levels of Ducted Equipment can be determined for various product Sound Components (ducted discharge, ducted inlet, casing radiated, and free inlet combined with casing radiated). These One-Third Octave Band Sound Power Levels shall be converted to Octave Band Sound Power Levels for the purposes of rating the equipment. Adjustments as outlined in 5.3.2 shall be added to the calculated Octave Band Sound Power Levels when required. 5.3.1 Converting One-Third Octave Sound Power Levels to Octave Sound Power Levels. Equipment Sound Power Levels for each One-Third Octave Band shall be determined from Sound Pressure Level data acquired in accordance with Section 4. The three One-Third Octave Band Sound Power Levels whose frequencies fall within the Octave Band are summed as: n= 3

Lwo(n ) = 10 log 10 [

æ Lw(n) ö

Σ 10ççè 10 ÷÷ø ] n=1

(5)

(3)

where: f

Note: It should be understood that the Duct End Corrections become numerically large for products with small effective duct diameters. This may tend to overstate the Sound Power Levels at low frequencies for such small products. For this reason, sufficient information is to be presented with the sound rating data to allow informed users of this information to identify the value of E for a specific unit ducted component.

where:

1.88

æ Co ö ÷÷ E = 10 log10 (1 + çç èπ f D ø

5.2.2 Duct End Correction Limit. When using the equation for Duct End Corrections in 5.2.1, the maximum value for E shall not exceed 14 dB.

)

(4)

Lwo(n) = Sound Power Level in the nth Octave Band, dB Lw(n) = Sound Power Level in the nth One-Third Octave Band, dB n = One-Third Octave Band of interest in the Octave Band Each Octave Band Sound Power Level shall be rounded to the nearest decibel. 5.3.2 Method for Processing Data When Using an Acoustic Test Duct with an Acoustic Test Duct Elbow. If it is necessary to use an Acoustic Test Duct Elbow, the computed Octave Band Sound Power Levels shall be adjusted by adding the Atkins adjustments given in Appendix D to each Octave Band.


ARI STANDARD 260-2001

5.4 Mapped Sound Ratings To Be Presented. The Mapped Sound Ratings shall be published, printed or provided in a selection program.

c.

5.4.1 Base Unit Supply Fan Rating. This rating shall be considered representative of the total unit operation sound if Appurtenance and Other Sound Source effects are shown not to contribute to the sound component under test. 5.4.2 Appurtenance Ratings. Sound ratings for any Appurtenance effect upon the Base Unit must be based on data as specified in Section 4. A description of the Appurtenance and a description of all significant test details must be presented with the sound data. 5.4.3 Other Sound Source Ratings. Sound ratings for any Other Sound Source must be added to the Base Unit and any Appurtenance effects. The sound ratings are to be based on data as specified in Section 4. A description of all significant test details must be presented with the sound data. 5.4.4 Predicted Sound Ratings for Untested Fan Operating Points and Unit Sizes. With certain restrictions, sound ratings can be predicted for untested fan operating points and unit sizes. 5.4.4.1 Sound Estimation for Untested Fan Operating Points. The manufacturer may estimate Sound Power Levels and provide ratings for other supply fan operating points using an appropriate algorithm that is based on the Sound Power Levels determined by testing over the operational map. However, Sound Power Levels and ratings shall not be estimated for supply fan operating points where operational speeds, rpm [rev/s], static pressure, in H2O [kPa] and horsepower are greater than or less than the highest or lowest operational speed, rpm [rev/s], static pressure, in H2O [kPa] and horsepower tested. 5.4.4.2 Estimated Ratings for Untested Product Sizes or Appurtenances. Tested product data may be used to estimate the Sound Power Levels and ratings of an untested size of the same product line as long as: a. b.

The fans are of the same geometric family The cabinet size, Appurtenances, or geometric scaling from one product size to another does not invalidate

“scaling laws” based on the fan similarities The sound levels of the two unit sizes tested and used for interpolation do not differ by more than 5 dB

Note: It shall be up to the manufacturer to test a sufficient number of product sizes in a given product line to assure an accurate method of prediction. 5.5 Determination of Octave Band Duct End Correction Levels for Ratings. Octave Band Duct End Correction levels shall be published with ducted discharge and/or ducted inlet rating(s). 5.5.1 Procedure for Calculating Octave Band Duct End Correction levels. Using the methodology of Equation (5) to calculate Octave Band levels of both the test unit One-Third Octave Sound Power Levels with the Duct End Correction levels added and the test unit One-Third Octave Sound Power Levels without Duct End Correction added, the difference in these octave levels are the Duct End Correction levels. Eo(n) = Lwc(n) – Lw(n)

(6)

where: Eo(n) = Duct End Correction, dB, for nth Octave Band Lwc(n) = Octave Band Sound Power Level, dB, with Duct End Correction applied for nth Octave Band Lw(n) = Octave Band Sound Power Level, dB, for nth Octave Band without Duct End Correction applied Note: Value shall not exceed level set in 5.2.2. Section 6. Minimum Data Requirements for Published Sound Ratings 6.1 Minimum Data to be Included in Published Sound Ratings. The following is a list of data required to document the ducted noise ratings supplied per this standard: a. b. c. d.

Unit configuration, Base Unit, Appurtenances and other sources Octave Band Sound Power Levels, dB Octave Band Duct End Corrections, dB (see AMCA Standard 300, Appendix C.9) and how duct was terminated in the reverberation room Duct internal height, width and length dimensions, ft [m]

9


ARI STANDARD 260-2001

e. f. g. h.

Acoustic Test Duct Elbow Octave Band correction (if used) Acoustic Test Duct Elbow internal height and width dimensions (if used), ft [m] Fan speed, rpm [rev/s], fan static pressure, in H2O [kPa], and fan motor BHP for each test point Component under test, supply, return or casing radiated

Note: The Octave Band data shall be rounded to the nearest decibel. 6.2 Verification of Published Sound Ratings. Any equipment selected at random and tested in a suitably qualified laboratory in accordance with this standard shall have a sound rating not higher than its published sound rating.

10

Section 7. Conformance Conditions 7.1 Conformance. While conformance with this standard is voluntary, conformance shall not be claimed or implied for products or equipment within its Purpose (Section 1) and Scope (Section 2) unless such claims meet all of the requirements of the standard.


ARI STANDARD 260-2001

APPENDIX A. REFERENCES - NORMATIVE A1 Listed here are all standards, handbooks, and other publications essential to the formation and implementation of the standard. All references in this appendix are considered as part of this standard. A1.1 AMCA Standard 300-96, Reverberant Room Method for Sound Testing of Fans, 1996, Air Movement And Control Association, 30 West University Drive, Arlington Heights, IL, 60004-1893, U.S.A. A1.2 ANSI/AMCA Standard 210-99, Laboratory Methods of Testing Fans for aerodynamic performance Rating, 1999, American National Standards Institute/Air Movement And Control Association, 11 West 42nd Street, New York, NY 10036 U.S.A./30 West University Drive, Arlington Heights, IL, 60004-1893, U.S.A. A1.3 ANSI Standard S1.11-1986 (R1996), Specifications for Octave -Band and Fractional Octave-Band Analog and Digital Filters, 1993, American National Standards Institute, 1986, 11 West 42nd Street, New York, NY, 10036, U.S.A. A1.4 ANSI Standard S12.31-1990 (R1996), Precision Methods for the Determination of Sound Power Levels of Broad-Band Noise sources in Reverberation Rooms, 1996, American National Standards Institute, 11 West 42nd Street, New York, NY 10036, U.S.A. A1.5 ANSI Standard S12.32-1990 (R1996), Precision Methods for the Determination of Sound Power Levels of Discrete-Frequency and Narrow-Band Noise Sources in Reverberation Rooms, 1996, American National Standards Institute, 1990, 11 West 42nd Street, New York, NY, 10036, U.S.A. A1.6 ARI Standard 210/240-94, Unitary Air Conditioning and Air-Source Heat Pump Equipment, 1994, Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A. A1.7 ARI Standard 250-2001, Performance And Calibration Of Reference Sound Sources, 2001, Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A.

A1.8 ARI Standard 280-95, Requirements for the Qualification of Reverberant Rooms in the 63 Hz Octave Band, 1995, Air-Conditioning and Refrigeration Institute, 1995, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A. A1.9 ARI Standard 340/360-2000, Commercial and Unitary Air-Conditioning and Heat Pump Equipment, 2000, Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A. A1.10 ARI Standard 430-99, Central-Station AirHandling Units, 1999, Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A. A1.11 ARI Standard 440-98, Room Fan-Coils and Unit Ventilators, 1998, Air-Conditioning and Refrigeration Institute, 1997, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A. A1.12 ASHRAE - Algorithms for HVAC Acoustics, 1989, American Society of Heating, Refrigerating and Air-Conditioning Engineers, 1791 Tullie Circle NE, Atlanta, GA, 30329-2305, U.S.A. A1.13 ASHRAE Terminology of Heating, Ventilating, Air-Conditioning and Refrigeration, Second Edition, 1991, American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc., 1791 Tullie Circle, NE Atlanta, GA. 30329. U.S.A. A1.14 ASHRAE Standard 37, Methods of Testing for Rating Unitary Air Conditioning and Heat Pump Equipment, 1998, American Society of Heating, Refrigeration, and Air-Conditioning Engineers, Inc., 1791 Tullie Circle, NE Atlanta, GA 30329. U.S.A. A1.15 Iqbal, M.A., Willson, T.K., Thomas, R.J. The Control of Noise in Ventilation Systems: a designer’s guide, 1977, E. & F. N. Spon Ltd, 11 New Fetter Lane, London EC4P 4EE, Great Britain A1.16 ISO 13256-1: 1998, Water-source heat pumps – Testing and Rating for Performance – Part 1: Water-to-Air and Brine-to-Air Heat Pumps, 1998, International Organization for Standardization, Case Postale 56, CH-1211, Geneva 21 Switzerland.

11


ARI STANDARD 260-2001

APPENDIX B. REFERENCES - INFORMATIVE B1 Listed here are standards, handbooks and other publications which may provide useful information and background but are not considered essential. References in this appendix are not considered part of the standard. B1.1 ANSI/ARI Standard 300-2000, Sound Rating and Sound Transmission Loss of Packaged Terminal Equipment, 2000, American National Standards Institute/Air-Conditioning and Refrigeration Institute, 11 West 42nd Street, New York, NY, 10036, U.S.A. 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A.

12

B1.2 ARI Standard 310/380-93, Packaged Terminal Air-Conditioners and Heat Pumps, 1993, Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A. (CSA-C744-93) (ANSI/ARI 310/380-93). B1.3 ARI Standard 880-98, Air Terminals, 1998, Air-Conditioning and Refrigeration Institute, 4301 North Fairfax Drive, Suite 425, Arlington, VA, 22203, U.S.A.


ARI STANDARD 260-2001

APPENDIX C. ARI STANDARDS ON SOUND - INFORMATIVE C1.

Purpose. Table C1 following lists current ARI Sound Standards. TABLE C1. ARI STANDARDS ON SOUND ARI SOUND STANDARD 250

TITLE

EQUIPMENT COVERED

REFERENCE TEST METHODS

Performance And Calibration of Reference Sound Sources Sound Rating of Ducted Air Moving and Conditioning Equipment

Reference Sound Sources Ducted air-conditioning equipment containing fans

AMCA 300-96; ANSI S12.3290 (R1995)

270

Sound Rating of Outdoor Unitary Equipment

Unitary air-conditioners and heat pumps under 135,000 Btu/h

275

Application of Sound Rated Outdoor Unitary Equipment Requirements for the Qualification of Reverberant Rooms in the 63 Hz Octave Band Sound Rating and Sound Transmission Loss of Packaged Terminal Equipment

Same as 270-95

ANSI S12.3290 (R1995); ISO 3742-1988 ARI 270-95

Packaged terminal air-conditioners and packaged terminal heat pumps

ANSI S12.32 (1995); ASTM E90 – 1990

350

Sound Rating of Non-Ducted Indoor Air-Conditioning Equipment

ANSI S12.3290 (R1995)

370

Sound Rating of Large Outdoor Refrigerating and AirConditioning Equipment Method of Measuring Sound and Vibration of Refrigerant Compressors Methods of Measuring Machinery Sound Within Equipment Rooms Air Terminals

1) Unitary equipment (unlimited size) 2) Packaged terminal equipment 3) Water-source and ground water-source heat pumps All outdoor ARI-type equipment not covered by ARI Standard 270-95

ANSI S12.3290 (R1995); ISO 3745-1977 External drive and hermetic-type compressors ANSI S12.32 (1995); ISO 3745-1977 Complete water-chilling systems located in a defined None space Ducted air control and distribution devices not ANSI S12.31including the central station fan(s) 90

Procedure for Estimating Occupied Space Sound Levels in the Application of Air Terminals and Air Outlets Rating of Air Diffusers and Air Diffuser Assemblies

Ducted air control distribution devices not including ARI 880-98 the fan(s)

260

280

300

530

575 880

885

890

Reverberant Rooms

Ducted diffuser and diffuser assemblies connected to ARI 890-94 remote forced air source

13


ARI STANDARD 260-2001

APPENDIX D. ATKINS SOUND ATTENUATION ADJUSTMENTS FOR ACOUSTIC TEST DUCT ELBOWS1 - NORMATIVE

1

14

Reference:

Iqbal, M.A., Willson, T.K., Thomas, R.J. The Control of Noise in Ventilation Systems: a designer’s guide, 1977, E. & F. N. Spon Ltd, 11 New Fetter Lane, London EC4P 4EE, Great Britain


ARI STANDARD 260-2001

APPENDIX E. EFFECTS OF OTHER SOURCES - NORMATIVE E1 Refrigerant Circuit Related Sound Sources. For the purpose of this standard, refrigerant circuit related Sound Sources are identified and defined only in reference to the ARI thermal rating standard operation point for a given product. If a product is operated at the standard thermal rating conditions* and the sound from the refrigerant circuit contributes 1 dB or less (in any One-Third Octave Band) to the supply fan sound at that operating point, the supply fan (without the refrigerant circuit effects) can be used to describe the product at any other fan operating condition across the map. If there is a contribution to the supply fan spectrum at that point, the spectrum of the refrigerant circuit Sound Source must be defined. That specific refrigerant circuit sound spectrum is to be added to the supply fan sound spectrum at all supply fan conditions. The sound spectrum for a refrigerant circuit related Sound Source is typically difficult to obtain due to contamination from the supply fan sound spectrum. To help avoid supply fan contamination to the refrigerant circuit related sound spectrum, the supply fan may be operated at a quieter operating point or turned off while artificially maintaining operation of the refrigerant circuit. Refrigerant circuit operation may be artificially maintained as defined by the note. *Note: This standard recognizes the difficulty of operating products at standard thermal rating conditions while conducting tests in acoustic test facilities. To identify the effects of secondary sources, this standard allows standard thermal rating conditions to be approximated in the acoustic test facility. This approximation can be obtained by artificially controlling the refrigeration circuit to match the compressor inlet and discharge saturation temperatures of Âą 5.0 oF [Âą 2.8oC ] that exist during a standard thermal rating test of the product. During refrigerant circuit operation, observe and record compressor inlet superheat. If necessary (and possible) adjust the superheat to avoid liquid slugging of the compressor(s) and associated noise.

E2 Return or Exhaust Fans in Return Duct. These are classified in this standard as Other Sound Sources. The noise generated by return and/or exhaust fans in the return duct shall be determined as follows: E2.1 Discrete Speed Fan or Multiple Discrete Speed Fan (fan that is directly coupled to a motor shaft that has 1 or more speed taps). The sound map on this type of fan varies with fan speed. The fan speed depends on the discrete speed tap and the amount of speed slip between the stator and rotor fields. The speed slip increases as the load on the motor increases. This generates a sound map that is a curve for each discrete fan speed. Determine the sound spectrum in each One-Third Octave Band for each fan speed per the requirements of 4.2.1 of ARI Standard 260 at fan operating points determined by the airflow and negative return duct static pressure. The return duct noise shall be the combination of the noise generated from the supply fan in the return duct and the noise generated by the return or exhaust fan in the return duct at the respective running conditions of each fan. E2.2 Variable Speed Fans (Fans that can run at an Infinite Number of Speeds Depending on Variations in Sheave Sizes or Variations in the Electrical Input Signal to the Motor). Determine the sound spectrum in each One-Third Octave Band for each fan speed per the requirements of 4.2.1 of ARI Standard 260 at fan operating points determined by the airflow and negative return duct static pressure. The return duct noise shall be the combination of the noise generated from the supply fan in the return duct and the noise generated by the return or exhaust fan in the return duct at the respective running conditions of each fan.

15


ARI STANDARD 260-2001

APPENDIX F. SUPPLY FAN MODULATION DEVICE EFFECTS NORMATIVE F1 Modulation Device Insertion Effects. This test identifies the acoustic effects of inserting a modulation device (such as inlet guide vanes at the fully open position) in the fan airflow. It does not measure the effects of actual modulation. Testing is conducted with the modulation device fully open (for guide vanes fully open) across the entire supply fan map. F2 Modulation Device Modulation Effects. This test provides representative modulated system curves for the product with a mechanical modulation device. This test is defined for various percentages of modulation of a modulation device along the same system curve as defined for the insertion effect. It can be conducted for two additional system curves, if desired.

16

Modulation device insertion effects shall first have been defined, at a minimum, along a single constant system curve. The initial point of the system curve shall be on the highest fan speed curve with the test point (static and airflow) being mid-way between stall and full open flow. Tests shall be conducted at this point with the modulation device fully open. Additional points along the system curve are obtained by operating the supply fan at other speeds defined in the original supply fan map with the modulation device at various degrees of closure. Additional tests are conducted at ¼, ½, ¾, and fully close guide vane settings, applying the same system load line. Additional system lines may be tested, starting at a test point along the highest speed curve nearest the maximum efficiency point and at a more wide open point as defined by the manufacturer, if desired.


ARI STANDARD 260-2001

APPENDIX G. METHOD OF PROCESSING ACQUIRED DATA – NORMATIVE Note: Sections refer to ARI Standard 260. One-third Octave Band Sound Pressure Test Data. (Sec 4)

Convert One-Third Octave Band Sound Pressure to One-Third Octave Band Sound Power (Sec 5.2)

Yes Ducted Component No

Calculate Duct End Correction for Each One-Third Octave Band (Sec 5.2.1 & 5.2.2)

Add Duct End Correction to Each One-Third Octave Band (Sec 5.2)

Convert One-Third Octave Band Sound Power to Octave Band Sound Power (Sec 5.3 & 5.3.1)

Convert One-Third Octave Band Sound Power to Octave Band Sound Power (Sec 5.3 & 5.3.1)

Yes

Convert One-Third Octave Band Sound Power to Octave Band Sound Power (Sec 5.3 & 5.3.1)

Yes

Test Duct Elbow No

Add Elbow Correction to Each Octave Band (Sec 5.3.2)

Test Duct Elbow No

Add Elbow Correction to Each Octave Band (Sec 5.3.2)

Subtract Octave Band Sound Power with Duct End Correction – Octave Band Sound Power Without Duct End Correction (Sec 5.5)

Published Octave Band Sound Power Ratings for Non Duct Sound Components (Sec 6.1)

Published Octave Band Sound Power Ratings for Ducted Component (Sec 6.1)

Published Octave Band Duct End Correction Data (Sec 6.1)

17

ARI-260-2001-SOUND RATING OF DUCTED AIR MOVING AND CONDITIONING EQUIPMENT  

SOUND RATING OF DUCTED AIR MOVING AND CONDITIONING EQUIPMENT Standard 260 4301 NORTH FAIRFAX DRIVE l ARLINGTON, VIRGINIA 22203

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